Pen-type injector having an electronic control unit

ABSTRACT

An injection device ( 2 ) having a drive mechanism ( 42 ) to expel selectively a dose of medicament from a medicament cartridge ( 40 ) through a needle arrangement is disclosed. The injection device ( 2 ) also comprises a processor to control the drive mechanism ( 42 ), a dispense button ( 18 ) to generate a signal to the processor to cause the medicament to be expelled and a priming detector to detect a predetermined orientation of the injection device. When the predetermined orientation is detected the processor will only actuate the drive mechanism ( 42 ) to expel a small amount of medicament.

The present invention relates to improvements in an injection device,and in particular to improvements in a portable injection device fordispensing controlled quantities of a medicament.

Typically such injection devices are used by those suffering fromdiabetes to administer a dose of insulin or insulin-type medicine tothemselves. It will be understood that such injection devices aresuitable for the injection of other medicines.

At one time, such doses were administered by use of a disposablesyringe; the syringe first being filled from a separate phial or othercontainer and then used to inject the dose. However, there were a numberof difficulties in such an arrangement. In particular, such anarrangement was not suitable for the infirm. For others, the socialstigma associated with such syringes made their public use problematic.

To overcome these difficulties a number of so-called pen-type injectorshave been developed. These devices are small, being capable of beingcarried in a jacket pocket or the like and allow a number of doses to beobtained from a cartridge or ampoule contained within the injector. Thepresent invention has particular application to such pen-type injectors.

While such pen-type injectors are a considerable improvement upondisposable hypodermic syringes, problems nevertheless remain. It is anadvantage of the present invention that it eliminates, or at leastsubstantially reduces such problems. The present invention also providesfor improved ease of use and improved interaction with a user.

The invention will now be described, by way of example only, withreference to the accompanying drawings; in which:

FIG. 1 shows a plan view of a pen-type injector in accordance with thepresent invention;

FIG. 2 shows a similar view to FIG. 1 with an end cap of the injectoromitted;

FIG. 3 shows a cross-sectional view of the injector of FIGS. 1 and 2;and

FIG. 3A shows a view similar to that of FIG. 3 with a filled cartridgein the injector.

Referring first to FIGS. 1 to 3, there can be seen a pen-type injector 2in accordance with the present invention. The injector 2 comprises amain housing 4 to which is releasably secured an end cap or cover 6.

At a first end of the main housing 4 there is provided a control panelregion 8. This region includes a display panel 10, typically a LCDdisplay, and a first dose button 12 and a second dose button 14, thefirst and second dose buttons being operated to increase or decrease adose of medicament to be delivered. The control panel region 10 in theillustrated embodiment also includes an arm button 16.

At the first end of the main housing there is also provided a dispensebutton 18. Preferably, when not depressed, the dispense button 18 isflush with the main housing 4.

Along a longitudinal axis of the injector 2, to each side of the controlpanel region 10 are provided a number of grooves or recesses 20. Theseaid in the gripping of the injector 2 by a user.

At a second end of the main housing 4 a needle unit 22 is releasablysecured to the main housing. The second end of the main housing 4 isalso provided with a shaped portion 24.

In use a cartridge 40 or ampoule of medicament is stored in the housing4 behind the shaped portion 24. For preference, the shaped portion istransparent to permit the cartridge 40 to be seen by a user.

A prime button 26 is also provided on the second end of the housing 4.It will be understood that when the end cap 6 is in place over thesecond end of the housing, it will not be possible inadvertently todepress the prime button 26 or to be pricked by the needle unit 22. Acover detection switch 28 may also be included at the second end of themain housing 4 to detect whether the end cap or cover 6 is in place ornot.

In FIG. 3, there can be seen a priming contact 30, an arm contact 32, afirst dose contact 34 and a second dose contact 36 corresponding to therespective buttons. A dispense contact 19 corresponding to the dispensebutton 18 is also shown.

With reference to FIG. 3 it may be seen that there is provided asuitable location for a power source 38 such as a battery or batteries.There is also a suitable region in which a cartridge 40 or ampoule ofmedicament is to be located. This region may be accessed by way of theremovable shaped portion 24 of the main housing 4 to allow forreplacement of the cartridge 40 or ampoule as required by the user.

In a third region of the main housing 4 there is provided a drivemechanism 42 which operates from the power source 38 and acts upon thecartridge 40 or ampoule of medicament.

The cartridge 40 or ampoule comprises a container 44 or sleeve closed atone end by a cover 46 at a head end thereof, and sealed at the other bya movable bung 48 or stopper. When in position, the needle unit 22pierces the cover 46 and movement of the bung 48 towards the cover 46will cause the medicament contained within the cartridge 40 or ampouleto be expelled. The cartridge may be a 3 ml cartridge in accordance withISO/FDIS 11608 Part 3, or any other suitable cartridge to suit theinjector.

Movement of the bung 48 or stopper is caused by movement of a piston orplunger 50 forming a part of the drive mechanism 42. The piston orplunger 50 is movable between a first fully withdrawn position (notshown) which allows for the replacement of the cartridge 40 or ampouleand a second fully extended portion in which as much medicament aspossible has been expelled from the cartridge 40 or ampoule. An end stopswitch 52 may be provided in the main housing 4 to detect when thepiston 50 is in the fully withdrawn position. Tripping of the switch endstop 52 may release a catch or other fastening device to allow access tothe main housing 4 for replacement of the cartridge 40.

The drive mechanism 42 is operated by a motor 54 under the control of anelectronic control unit (not shown). The motor 54 should be reversiblein order to allow the piston 50 to be moved between the first and secondpositions. In FIG. 3, the motor 54 can be seen to drive the piston 50 byway of a gear train 42, such that rotation of a third rotor 58 causesthe piston 50 to be moved in relation to the third rotor 58.

Preferably, the user can feel the vibration of the motor 54 and theassociated drive mechanism 42 and/or hear them in operation. In this wayan added degree of confidence in the fact of the operation of theinjector 2 is provided to the user.

The functionality of a pen-type injector in accordance with the presentinvention will now be described, in particular with reference to FIGS.1, 2 and 3.

The injector 2 is provided with an electronic control unit. Theelectronic control unit is coupled both to the drive mechanism and auser interface. The user interface includes the display panel 10 as wellas the user operable buttons (and associated contacts). The electroniccontrol unit is microprocessor based. Either volatile or non-volatilememory may be used for storage of ‘dose history’ and patient specificinformation. It will be understood that depression of the user operatedbuttons will cause associated signals to be sent to the electroniccontrol unit, that is when the prime button 26 is depressed a primesignal will be sent to the electronic control unit.

The electronic control unit is preferably powered from the injectorpower source 38.

The injector 2 preferably also includes a port for communication betweenthe electronic control unit and an external apparatus such as a personalcomputer.

The injector 2 also has a priming detection facility, (such as a tiltswitch or accelerometer) to identify when the injector 2 is inverted. Ondetection of an inverted position (needle up) the injector 2 willautomatically change state to be ready for priming. Priming may beinitiated by depression of the prime button 26 to cause a fixed smalldispense action. The electronic control unit may cause a speaker tosound when the prime button 26 is depressed.

The prime button 26 is inactive at all other times. When the primebutton 26 is active, all other buttons in the control panel region areinactive, that is those buttons which are to be used to set or dispensea dose. In other words, when the prime button 26 is active, theelectronic control unit or processor will only actuate the drivemechanism 42 to cause a fixed small dispense action

The electronic control unit may cause a speaker to sound when the armbutton 16 is depressed for a sufficient period of time to provideaudible feedback for the user.

The function of the arm button 16 is to make the dose button 18 active.The arm button is preferably held down for a predetermined period oftime before the injector 2 becomes armed. The armed status mayadditionally be shown on the display panel 10. The functionality of thearm button is preferably linked to the cover detection switch 28 suchthat the arm button 16 will only function to arm the injector 2 when thecover 6 is not present.

Additionally, in a preferred embodiment, a clock within the electroniccontrol unit will detect whether the dose button 18 has been pressedwithin a specified time interval following arming of the injector 2. Ifthe dose button 18 has not been depressed within the specified timeinterval the electronic control unit will disarm the injector 2.Alternatively, if the arm button is depressed a second time within apredetermined time period by the user, the injector will be disabled.

In an alternative embodiment, the dose button 18 may function as both aprime button and the dose button. When the priming detector is actuated,by the injector 2 being oriented needle up, the dose button 18 wouldchange function to that of the prime button of the previous embodiment.

The buttons of the injector 2 are preferably tactile in nature toprovide sensory feedback to the user.

The display panel 10 is typically an LCD display and will providealphanumeric and graphical information relating to the operation of thedevice. The display panel 10 preferably indicates the selected dosequantity, the previous dose quantity and the time elapsed since theprevious dose was administered. Typically, the time elapsed since theprevious dose is limited to a time period within the preceding 48 hours,though other time periods are possible.

Additional information which may be displayed includes:

-   -   that the injector is armed and ready to dispense (graphical)    -   that the injector is dispensing (graphical)    -   that the injector has dispensed the selected dose and that a        user should wait before removing the needle from their body    -   that this waiting period has elapsed    -   the dose history, typically for the last 48 hours, in terms of        the dosage taken and the elapsed time between doses    -   the quantity of medicament remaining in the cartridge,        preferably in terms of dosage units of the medicament.    -   that the device is in the priming position (either in addition        to or instead of the acoustic indication noted above)    -   the speaker volume setting, for example high, low or muted.    -   that the injector is nearing the end of its life (for example a        battery power level indication—graphical or countdown in terms        of the number of days or complete operating cycles to a        predetermined expiry of the product life—alphanumeric).    -   that the needle is probably blocked    -   that replacement of the cartridge 40 is in progress    -   that the dose selected is the maximum available in the cartridge        40    -   that the maximum dose available is less than the dose expected.

The display panel 10 may offer a user a choice of language options asappropriate for the market and/or user. The text displayed may includethat noted above and/or further information. The language option may bepre-programmed or selectable by a user. The user may preferably selectthe language option by means of a menu provided on the display panel 10.

The currently selected dose value, the previously used dose value andthe time (in hours) since the previous dose was dispensed, may all beshown clearly at the same time, in large, easy-to-read characters on thedisplay. Preferably, the display is also provided with a backlight.

The display 10 preferably provides a graphical indication that theselected dose is being dispensed. This may be achieved, for example, aseither an animated graphic or a countdown (or a combination of both).

The control buttons have a number of functions. The dose buttons 12, 14allow a user to select a desired dosage. The dose arm button 16 allows auser to confirm selection of a desired dosage. The first dose button canincrement the dosage level and the second dose button can decrement thedosage level. The dose dialling buttons 12, 14 may be pressed down (andheld for a short time, 1-2 seconds) to re-set a dose value to zero. Theuser can then dial up (or down) in single (or half) increments.

The dose dialling buttons 12, 14 are intended to be pressed once for asingle (or half) increment in the selected dose value. In an alternativeembodiment, pressing and holding one of the buttons will cause the dosevalue to start to scroll (up or down) in order to change the dose sizemore rapidly.

The dispense button 18 allows a user to initiate dispensing of thedosage. The primer button 26 dispenses a unit of dosage from thecartridge 40. Thus, if any air is trapped in the injector 2 this can beexpelled by use of the prime button 26. A door release catch is providedto allow access to the cartridge 40.

1. An injection device, comprising: a drive mechanism to expelselectively a dose of medicament from a medicament cartridge through aneedle arrangement; a processor to control the drive mechanism; adispense button to generate a signal to the processor to cause themedicament to be expelled; and a priming detector to detect apredetermined orientation of the injection device, characterised in thatwhen the predetermined orientation is detected the processor will onlyactuate the drive mechanism to expel a small amount of medicament.
 2. Aninjection device according to claim 1, comprising: a prime button togenerate a signal to actuate the drive mechanism to expel the smallamount of medicament.